1. Field of the Invention
The present invention relates to fastener driving tools, and particularly concerns such tools and assemblies in which the fasteners comprise nails. Thus, the tool according to the invention may comprise a nailer. However, the invention also concerns other types of fasteners, including pins, staples, screws, rivets, etc.
2. Description of the Related Art
Many fastener driving tools include a driver that is propelled rapidly against a fastener to drive a fastener from the tool into a workpiece. The driver may comprise a piston, or a ram (impact member), for example. The driver may be propelled in any of a variety of ways, including, but not limited to, pneumatically, by combustion, by means of a strap or chain, by means of a separate piston, or by means of one or more flywheels, for example.
For many years, fastener driving (firing) tools have included a feature whereby a fastener cannot be fired (driven) from the tool unless a nose part of the tool is retracted. This is intended to ensure that the nose part of the tool is pushed against a workpiece, such that the nose part is retracted, before a fastener can be fired from the tool. Some fastener driving tools also include a mechanical detector to detect whether or not a fastener is present in an outlet passage of the tool. If a fastener is not present, a nose part of the tool is prevented from retracting, and thus the tool is prevented from firing a fastener. This is sometimes ret erred to as “dry-fire lock-out”, and is an additional feature intended to ensure that if the tool is fired, the energy generated by the tool is (at least partially) expended in firing a fastener from the tool and does not need to be absorbed by the tool. Fastener driving tools including a fastener detector are disclosed in the following U.S. Pat. Nos. 3,606,128; 5,167,359; 6,267,284 B1; 7,059,507 B2; and in U.S. Patent Application Publication US 2007/0290019.